Hello,
I've got a current UM system up and running without too many issues on testpackage 4.13. But there are still plenty of bugs.
I'm guessing one of the main reasons why ROS is used is for UM and radius, for most ISP/WISP (small companies). I would really like to make a suggestion to the MK team, and that is to really get a stable/bug free version. You guys are on to something good here, so please don't let the system fail and drop off.
If you need to charge more for your licence then do so, but please concentrate on getting something that works 100% - if need be recode the whole package.